It is the most common cause of mucormycosis in humans and occasionally infects other animals.

The virus circulates among rodents and vector mosquitoes and occasionally infects humans.

"Flu viruses circulating in swine occasionally infect humans," says Bresee.

Many of these organisms are usually recovered from the soil but occasionally infect humans and animals.

Babesia bovis is a single-celled protozoan parasite of cattle which occasionally infects humans.

This species may occasionally infect man.

It occasionally infects other grasses including barley.

Though generally found in arthropods or rodents, certain viruses in this family occasionally infect humans.

Geophilic species are usually recovered from the soil but occasionally infect humans and animals.